Update and install required packages:
$ apt-get update -y
$ apt-get install -y g++ gcc make libc6-dev patch openssl ca-certificates libreadline6 libreadline6-dev curl zlib1g zlib1g-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt1-dev autoconf libc6-dev libgdbm-dev libncurses5-dev automake libtool bison pkg-config libffi-dev
Install ruby-build
$ git clone git://github.com/sstephenson/ruby-build.git /tmp/ruby-build
$ cd /tmp/ruby-build/
$ ./install.sh